If you have warm temperatures during the day but cold nights and want to add plants to your Fall or Winter garden you can start your seedlings in small containers stored inside clear plastic totes. Take the totes outside before you leave in the morning so they can get a day's worth of sunlight and build up cold tolerance then bring them inside at night.

This idea comes from homesteading weblog The Prairie Cottage. They recommend grouping seedlings into plastic totes according to their cold tolerance. That way you can bring in your most vulnerable plants well before sunset while other plants may be fine for another hour or two. Eventually most of your plants will grow and build up their cold tolerance so they can be planted in the soil and you can flip the clear tote over as an improvised cold frame while the plant's root systems are getting established. The plastic totes may not seem like much but they will keep wind chill from hurting your plants as well as trap a little solar heat.